In the art of industrial parts washers of the ferris wheel type, parts to be washed are delivered into and removed from the washer on a parts conveyor. A ferris wheel is supported in the washer and has a plurality of angularly spaced parts receiving and supporting stations around its periphery. The ferris wheel and parts conveyor operate in synchronized step-by-step relation. During pauses in the ferris wheel rotation the successive stations are in registry with the conveyor and the conveyor operates to deliver a part into the station and remove a part from the station ahead of the part being delivered. A part thus received on the ferris wheel is carried by it during subsequent step-by-step movements through a washing zone, the part being gradually inverted as the wheel rotates, and jets of washing liquid are played on the part to clean it. The part eventually returns to the starting point and is discharged from the ferris wheel and another part takes its place in the station. One or more such ferris wheels may be provided in the washer.
The foregoing generally described arrangement is disclosed in U.S. Pat. No. 2,979,062. As the parts to be washed in such a machine are often fairly heavy, such as internal combustion engine cylinder heads and the like, there is a considerable mass to be started and stopped during the step-by-step rotation of the ferris wheel. In addition it is necessary to accurately align each parts supporting station on the ferris wheel with the parts conveyor in order to effect transfer from one to the other. The mass of the parts to be washed taken with the mass of the ferris wheel and its associated drive train presents problems in effecting smooth starting, stopping and proper registry of each station with the parts conveyor.
Two approaches to rotating the ferris wheel and stopping it with successive stations aligned with the parts conveyor have been suggested. One is disclosed in U.S. Pat. No. 2,979,062 wherein a drive wheel connected to the ferris wheel is provided with a series of holes near its periphery. An arm is swingably mounted adjacent the drive wheel and carries a cross-wise extending hydraulic cylinder and piston, the piston being shiftable into and out of the holes. Another hydraulic cylinder and piston are connected to the free end of the arm to swing it back and forth. Still a third cylinder and piston are arranged adjacent the drive wheel with the piston shiftable into and out of the holes to lock the drive wheel and consequently the station on the ferris wheel in alignment with the parts conveyor. Operation of the three cylinders is synchronized to rotate the drive wheel in a step-by-step manner and lock it in position to allow transfer of parts between the ferris wheel stations and the parts conveyors. According to the second approach two hydraulic cylinders and a rotary hydraulic actuator are utilized.
Both of these approaches are expensive and neither provides a smooth starting and stopping action.